Glossary of Important Terms – Microorganisms
Term -Definition
Microorganisms -Tiny living organisms not visible to the naked eye, including bacteria, viruses, fungi, protozoa, and algae.
Bacteria -Single-celled microorganisms that can be both helpful (e.g. in curd formation) and harmful (e.g. cause diseases).
Fungi -A group of microorganisms including molds and yeasts, which can decompose organic matter or cause infections.
Protozoa -Microscopic, single-celled animals that often live in water and can cause diseases like malaria and dysentery.
Algae -Plant-like microorganisms that can carry out photosynthesis; found in water bodies.
Viruses -Non-living outside the host, but can multiply inside living cells and cause diseases like cold and flu.
Pathogens -Disease-causing microorganisms.
Vaccination -The process of introducing a vaccine into the body to produce immunity against a disease.
Vaccine -A substance that stimulates the production of antibodies and provides immunity against one or several diseases.
Antibiotics -Medicines that kill or stop the growth of disease-causing bacteria.
Antibodies -Proteins produced by the body to fight against disease-causing organisms.
Lactobacillus -A type of bacteria used in the conversion of milk into curd.
Rhizobium -Nitrogen-fixing bacteria that live in the root nodules of leguminous plants.
Nitrogen Fixation -The process of converting atmospheric nitrogen into a usable form for plants.
Fermentation -A process in which microorganisms like yeast convert sugars into alcohol or acids.
Yeast -A fungus used in baking and brewing; helps in fermentation.
Penicillin -The first antibiotic discovered, obtained from the fungus Penicillium.
Alexander Fleming -The scientist who discovered penicillin in 1928.
Decomposer -Microorganisms that break down dead organisms and recycle nutrients back to the environment.
Biodegradable -Materials that can be broken down by microorganisms into simpler, harmless substances.
Communicable Diseases -Diseases that spread from one person to another via air, water, contact, or insects.
Food Preservation -Techniques used to prevent food spoilage by microorganisms (e.g., refrigeration, salting, pasteurisation).
Pasteurization -The process of heating milk to a specific temperature to kill harmful bacteria without changing its taste.
Louis Pasteur -The scientist who developed the process of pasteurization and made advances in vaccination.
Nitrogen Cycle -A natural process involving the conversion of nitrogen into various forms for use by plants and animals.
Probiotics -Beneficial bacteria that help in maintaining gut health.
Spoilage -The process of food becoming unfit to eat due to microbial action.
Food Poisoning -Illness caused by consuming contaminated food containing harmful microorganisms.
Host -An organism in which a microorganism (especially virus) lives and reproduces.
Epidemic -A disease that spreads rapidly among many people in a specific area.
Pandemic -A disease outbreak that spreads across countries or continents.
Carrier -A person or animal that harbors a disease-causing microorganism but shows no symptoms.
Inoculation -The act of introducing microorganisms into the body (usually via vaccine) to develop immunity.
Sterilization -The process of killing or removing all microorganisms from an object or area.
Antiseptics -Substances applied to living tissues to prevent the growth of microorganisms.
Contagious Diseases -Infections that can be spread from person to person by direct or indirect contact.
Airborne Diseases -Diseases spread through air via droplets (e.g., tuberculosis, common cold).
Waterborne Diseases -Diseases spread through contaminated water (e.g., cholera, typhoid).
Something To Know
A. Fill in the blanks:
- The study of microorganisms is known as Microbiology.
- The bread dough rises because of the production of Carbon dioxide.
- Pathogens are the microorganisms that cause diseases.
- Sodium benzoate and potassium metabisulphite are two chemical preservatives.
- Aspergillus is a fungus that causes food poisoning.
B. Match the following:
Answer
Column A Column B
- Ringworm (c) fungus
- Clostridium (a) food poisoning
- Anthrax (d) cattle
- Lactobacillus (e) curd
- Methane (b) biogas reactor
C. Tick (✅) the correct option.
- The process, that helps milk to last longer but does not kill all microbes present in it, is known as—
Vaccination
Bio-augmentation
Pasteurisation
Fermentation
Answer – Pasteurisation
- Rust of wheat is caused by—
Fungus
Virus
Bacteria
Protozoa
Answer – Fungus
- Medicines, containing killed or weakened pathogens, and used to prevent infectious diseases, are called—
Disinfectants
Antibiotics
Antibodies
Vaccines
Answer – Vaccines
- Which of the following reproduces only inside a host cell?
Virus
Protozoan
Alga
Bacteria
Answer – Virus
- A disease, caused by a virus, and spread by an insect, is—
Polio
Dengue
Rabies
Mumps
Answers – Dengue
D. Answer the following questions in brief:
- Why are viruses considered as being at the ‘borderline’ between living and non-living things?
Answer – Viruses are considered as the borderline between living and non-living things because they show characteristics of living organisms only when inside a host cell. Outside a host, they behave like non-living matter—they do not respire, grow, or reproduce on their own.
- What is fermentation? How is this process useful in the food and beverage industries?
Answer – Fermentation is the process in which microorganisms like yeast convert sugars into alcohol or acids in the absence of oxygen.
Uses:
In making alcohol and wine (by yeast)
In baking (to make bread soft and floffy)
In producing curd and cheese
- ‘In the absence of microorganisms the earth would become a heap of dead plants and animals.’ Justify this statement.
Answer – Microorganisms, especially decomposers, break down dead plants and animals into simpler substances. Without them, this natural recycling wouldn’t occur, and organic matter would keep accumulating, disrupting the ecosystem.
- Munna observes that the yield of wheat, growing in his field, has reduced in the current year. He gets the soil tested and the report confirms the deficiency of one particular nutrient. Accordingly, he is advised to grow peas after harvesting wheat.
(i) Name the nutrient found insufficient.
Answer – The nutrient found insufficient is nitrogen.
(ii) How do you think growing peas will help in replenishing the soil?
Answer – Growing peas will help because leguminous plants like peas have Rhizobium bacteria in their root nodules, which fix nitrogen from the atmosphere into the soil, enriching it for the next crop.
- Why does it take less time to prepare curd in summers as compared to preparing it in winters?
Answer – Curd forms faster in summer because the warm temperature speeds up the growth of Lactobacillus bacteria, which convert milk into curd.
- How are the following diseases transmitted?
(a) Malaria (b) Common cold (c) Tetanus (d) Typhoid
Ans. – (a) Malaria – Transmitted by female Anopheles mosquito.
(b) Common cold – Spread through air droplets or contact with infected surfaces.
(c) Tetanus – Enters the body through wounds and cuts contaminated with bacteria.
(d) Typhoid – Spread through contaminated food and water.
- What are antibiotics? How are they produced? Give two examples of these.
Answer – Antibiotics are medicines that kill or stop the growth of disease-causing bacteria.
They are produced by microorganisms like fungi and bacteria.
Examples: Penicillin and Streptomycin.
E. Answer the following questions.
- ‘Microorganisms are very useful in manufacturing different food items’. Explain.
Answer – Microorganisms play a vital role in the production of various food items. For example-
Lactobacillus bacteria help in converting milk into curd.
Yeast is used in baking as it produces carbon dioxide, making dough soft and spongy.
Yeast is also used in fermentation processes for making alcoholic beverages like wine and beer.
Microorganisms are involved in the production of vinegar, cheese, and pickles.
- Give reasons for the following-
(a) Yeast is added to the batter used to make ‘dosas’.
Answer – Yeast produces carbon dioxide gas during fermentation, which makes the batter soft and fluffy.
(b) It is important to brush one’s teeth before going to bed.
Answer – Brushing removes food particles and prevents the growth of harmful microorganisms that can cause tooth decay and bad breath.
(c) Reducing the quantity of salt in pickle can cause it to go bad soon.
Answer – Salt acts as a preservative. Lowering its quantity allows microorganisms to grow, leading to spoilage.
(d) Foods from puffed or enlarged cans should not be consumed.
Answer – Bulging cans are a sign of gas production by harmful bacteria inside the can, which can cause food poisoning.
(e) When using frozen food items, one should take out only the required quantities; thawed food should never be refrozen.
Answer – Refreezing thawed food allows microorganisms to multiply, increasing the risk of foodborne illnesses.
- How do communicable diseases spread? Suggest ways to prevent the following diseases-
Answer – Communicable diseases spread through-
Air (e.g., tuberculosis)
Water (e.g., cholera)
Contact with infected person/object (e.g., athlete’s foot)
Insect bites (e.g., malaria)
Prevention-
Tuberculosis – Avoid close contact with infected persons, ensure good ventilation and get vaccinated.
Athlete’s foot – Maintain proper hygiene, keep feet dry and avoid sharing footwear.
Cholera – Drink clean water, maintain food hygiene and practice good sanitation.
- What are pathogens? Name two pathogens each that cause diseases in (i) plants and (ii) animals.
Answer – Pathogens are disease-causing microorganisms.
In plants-
Bacteria – causes citrus canker.
Fungi – cause rust of wheat.
In animals-
Virus – causes foot and mouth disease in cattle.
Bacteria – causes anthrax.
- Mohan bought samosas from a roadside vendor and fell ill. What could be the reason, what is it called, and how can it be prevented?
Answer – Mohan likely suffered from food poisoning, caused by eating contaminated food. It results in vomiting, diarrhoea, and abdominal pain.
Prevention-
Avoid eating uncovered street food.
Ensure food is cooked and stored properly.
Maintain personal and food hygiene.
- Diseases the children are likely to suffer from-
(a) Ramu drinks unclean lake water.
Answer – Ramu may suffer from waterborne diseases like cholera or typhoid.
(b) Ashu maintains poor personal hygiene.
Answer – He may suffer from fungal infections like ringworm or skin infections.
(c) Pulkit is bitten by an infected street dog.
Answer – He may suffer from rabies, a viral disease.
(d) Sohan lives in a crowded area and is not protected against mosquitoes.
Answer – He may suffer from malaria or dengue, both spread by mosquito bites.
(e) Mohan was around people suffering from cold, one of whom did not cover his mouth.
Answer – Mohan may catch the common cold, a contagious viral infection spread through air.
Value Based Question
Soham and his wife are overjoyed after the birth of their daughter. They share their joy with their relatives and friends. Soham’s wife decides to take their daughter for her first round of vaccinations. However, Soham’s mother does not like the idea of putting the child through the discomfort of ‘injections’. Soham explains to his mother, in a polite and patient way, that this slight discomfort and pain is necessary as it shall ensure that the child lives a long and healthy life.
- Was Soham right in supporting his wife’s decision? List any two values that are demonstrated by his behaviour.
Answer – Yes, Soham was right in supporting his wife’s decision. Vaccination is an essential health measure that helps protect a child from several dangerous diseases, even though it might cause some temporary discomfort. By explaining the necessity of vaccinations to his mother in a polite and patient manner, Soham demonstrates values such as:
Responsibility: Soham is taking responsibility for his daughter’s health and well-being by supporting necessary medical procedures, which will protect her from potential life-threatening diseases.
Patience: Soham shows patience in explaining the importance of vaccinations to his mother, ensuring that she understands the reasoning behind the decision, even if she initially disagrees.
- How does vaccination help in providing immunity?
Answer – Vaccination helps provide immunity by introducing a small, harmless part of a pathogen (such as a dead or weakened virus, or a protein from the pathogen) into the body. This stimulates the immune system to produce antibodies. These antibodies “remember” how to fight that pathogen if the body is exposed to it in the future. This process builds immunity without causing the disease itself. As a result, the body is better prepared to fight off infections, making the individual less likely to get seriously ill.
- Find out the names of any five diseases that can be prevented by timely vaccination of children.
Answer – Polio
Measles
Hepatitis B
Diphtheria
Tetanus
These are just a few examples of diseases that can be prevented through routine childhood vaccinations, ensuring a healthier future for the child.
Something To Do
- Visit a nearby health centre, or contact a doctor. Find out the names of diseases for which vaccinations are available and the age at which they have to be given to the child.
Answer – Below is a list of common vaccinations and their recommended administration schedule:
BCG (Bacillus Chalmette-Guerin) – Given at birth to protect against tuberculosis.
Polio (OPV) – Given at birth, 6 weeks, 10 weeks, and 14 weeks.
Hepatitis B – Given at birth, 6 weeks, and 10 weeks.
DTP (Diphtheria, Tetanus, and Pertussis) – Given at 6 weeks, 10 weeks, and 14 weeks.
Hib (Haemophilus influenzae type b) – Given at 6 weeks, 10 weeks, and 14 weeks.
MMR (Measles, Mumps, Rubella) – Given at 9 months and a booster at 15 months.
Rotavirus – Given at 6 weeks, 10 weeks, and 14 weeks.
Chickenpox (Varicella) – Given at 12-15 months.
Hepatitis A – Given at 1 year.
Typhoid – Given at 2 years and above, as required.
- Genetic engineering is a branch of science in which microorganisms are being extensively used. Try to find out the role of microorganisms in genetic engineering.
Answer – In genetic engineering, microorganisms such as bacteria and fungi are extensively used for various purposes. The role of microorganisms in genetic engineering includes:
Gene Cloning: Microorganisms, especially E. coli (bacteria), are used as hosts for cloning genes. The foreign gene is inserted into a microorganism, which replicates and produces the desired protein.
Production of Recombinant Proteins: Microorganisms are engineered to produce recombinant proteins (e.g., insulin, growth hormones). These proteins are extracted for use in medicine.
Fermentation: Microorganisms are used in fermentation processes to produce various chemicals, antibiotics, and biofuels.
Bioremediation: Some microorganisms are genetically engineered to break down pollutants and toxins in the environment.
- Visit an animal health centre or a veterinarian (a physician for animals). Collect information about various vaccinations that are available for domestic animals (like cows) and pets (like dogs).
Answer – Common vaccinations for domestic animals and pets include:
For Cows (Livestock):
Brucellosis – Given to prevent brucellosis, a bacterial infection that causes reproductive issues in cattle.
Foot and Mouth Disease (FMD) – Prevents a viral disease that affects livestock, causing fever, blisters, and lameness.
Bovine Tuberculosis (TB) – Prevents tuberculosis, a chronic disease affecting cattle’s respiratory system.
For Dogs (Pets):
Rabies – A mandatory vaccination that prevents the fatal rabies virus.
Canine Distemper – A viral disease vaccination that protects against respiratory and gastrointestinal issues.
Parvovirus – Protects dogs from a severe viral infection that affects their intestines.
Leptospirosis – Prevents a bacterial infection that can lead to kidney and liver damage.
Kennel Cough – Protects against a respiratory infection common in places with many dogs.
- Write how the following methods of preservation work. Also, add two examples of foods that can be preserved by each of these methods.
Method | How it works | Examples (of food preserved) |
Pickling | Involves storing food in an acidic solution (vinegar or brine), which prevents bacterial growth. | Cucumbers, olives |
Ozone Treatment | Ozone gas kills bacteria, fungi, and viruses on the surface of foods, extending shelf life. | Fruits, vegetables |
Drying | Removes moisture from food, inhibiting the growth of microorganisms. | Dried fruits, dried herbs |
Adding Preservatives | Chemical preservatives are added to food to slow down spoilage caused by bacteria, mold, or yeast. | Processed meats, canned vegetables |
Canning | Food is sealed in airtight containers and heated to destroy microorganisms. | Canned beans, canned tomatoes |
Vacuum Packing | Air is removed from the packaging to prevent the growth of aerobic bacteria. | Vacuum-packed meat, fish |
Freezing | Food is stored at low temperatures, slowing down the growth of microorganisms. | Frozen vegetables, frozen ice creams |
Radiation | Ionizing radiation kills microorganisms and insects, extending shelf life. | Spices, dry fruits |
Salting | Salt draws moisture out of food, which prevents the growth of bacteria. | Salted fish, salted meat |
- Find out about the temperatures at which the following occur/exist/work:
Process | Temperature |
Decomposition | Occurs at temperatures between 20°C to 60°C (varies with environment) |
Pasteurisation | Typically occurs at 63°C to 85°C for a few minutes depending on the type of food |
Steamer | Water boils at 100°C to create steam |
Refrigerator | Generally works at 0°C to 4°C |
Deep Freezer | Works at -18°C or lower to keep food frozen |
Human Body | Average temperature is 37°C |
Additional Questions
Additional Questions and Answers
- How do microorganisms help in the production of bread and other bakery items?
Answer: Microorganisms, particularly yeast, are used in the production of bread and other bakery items. Yeast ferments the sugars in the dough, releasing carbon dioxide gas as a by-product. This gas gets trapped in the dough, causing it to rise and become light and airy. This process is known as fermentation. In addition to this, yeast also enhances the flavour of the bread.
- What is the role of microorganisms in the fermentation process?
Answer: Microorganisms, such as bacteria, yeast, and fungi, play a vital role in the fermentation process. During fermentation, microorganisms break down carbohydrates (such as sugars) in the absence of oxygen, releasing energy. This process produces various by-products, including alcohol (ethanol), acids (such as lactic acid), and gases (like carbon dioxide). These by-products contribute to the flavour, texture, and preservation of the food. Fermented foods include yogurt, bread, wine, and sauerkraut.
- What is the importance of probiotics in our diet? Name a few food items that contain probiotics.
Answer: Probiotics are live microorganisms that, when consumed in adequate amounts, confer a health benefit on the host (i.e., the human body). They help maintain a balance of good bacteria in the digestive system, aiding digestion, boosting immunity, and preventing the growth of harmful microorganisms. Foods that contain probiotics include yogurt, kefir, kimchi, sauerkraut, and pickles.
- Why are some microorganisms considered beneficial to humans, while others are harmful?
Answer: Beneficial microorganisms perform essential tasks that support human health. For example, some bacteria help in the digestion of food and the synthesis of vitamins in the gut. Others are used in the production of antibiotics, vaccines, and fermented foods. On the other hand, harmful microorganisms (pathogens) can cause diseases like malaria, tuberculosis, cholera, and typhoid by infecting the body and disrupting normal functions. The difference between beneficial and harmful microorganisms lies in their interactions with the human body—beneficial microorganisms promote health, while harmful ones lead to illness.
- What is bioremediation, and how do microorganisms contribute to this process?
Answer: Bioremediation is the process of using microorganisms to break down or neutralize pollutants, such as toxic chemicals, in the environment. Microorganisms such as bacteria, fungi, and algae have enzymes that can degrade pollutants, including petroleum, heavy metals, and pesticides, into harmless substances. This process is often used to clean up oil spills, polluted water, and contaminated soil.
- What are the benefits of using microorganisms in the production of antibiotics?
Answer: Microorganisms, particularly fungi and bacteria, are used to produce antibiotics that fight bacterial infections. The most well-known antibiotic, penicillin, is derived from the fungus Penicillium. These antibiotics inhibit the growth of harmful bacteria by disrupting their cell walls or other essential functions. The production of antibiotics has significantly improved human health by treating infections that would otherwise be fatal.
- Explain how microorganisms contribute to the process of nitrogen fixation.
Answer: Nitrogen fixation is the process by which certain microorganisms convert atmospheric nitrogen into forms that plants can use, such as ammonia or nitrates. Rhizobium bacteria form symbiotic relationships with leguminous plants (e.g., peas, beans), fixing nitrogen in the plant roots. These bacteria convert nitrogen from the air into compounds that plants can absorb and use for growth, which also improves soil fertility.
- What are some common methods used to prevent food spoilage caused by microorganisms?
Answer: Several methods are used to prevent food spoilage caused by microorganisms:
Refrigeration and freezing slow down the growth of microorganisms.
Canning involves sealing food in airtight containers and heating it to destroy harmful microbes.
Salting and pickling create an environment that inhibits microbial growth.
Drying removes moisture, which is essential for the growth of bacteria and molds.
Adding preservatives like citric acid, vinegar, or sodium benzoate helps prevent microbial growth.
Sterilization involves heating food to kill microorganisms before packaging.
- How do microorganisms contribute to the production of alcoholic beverages?
Answer: Microorganisms, especially yeast, play a critical role in the production of alcoholic beverages. Yeast ferments the sugars present in fruits or grains, producing ethanol (alcohol) and carbon dioxide. In the production of wine, yeast ferments the sugars in grape juice. In beer production, yeast ferments the sugars in malted barley. The alcohol produced during fermentation is what gives these beverages their alcoholic content.
- Why is it important to store food properly to prevent microbial contamination?
Answer: Proper food storage is essential to prevent the growth of harmful microorganisms that can lead to foodborne illnesses. Storing food at the correct temperature (e.g., refrigerating perishable items) slows down microbial growth. Properly sealing food in airtight containers, avoiding cross-contamination, and ensuring cleanliness during food preparation can also reduce the risk of contamination by bacteria, molds, or fungi. Consuming improperly stored food can lead to food poisoning or other health issues.
- What are the different types of microorganisms involved in food spoilage, and how do they affect food?
Answer: Several types of microorganisms are involved in food spoilage:
Bacteria: They can cause food to rot, sour, or develop unpleasant odours. Examples include Salmonella, Escherichia coli, and Listeria.
Molds: Fungi like molds can grow on bread, cheese, and fruits, causing discoloration and an off taste.
Yeasts: They can cause fermentation in foods like fruits and juices, leading to sourness and bubbling due to gas production.
Viruses: Though less common in food spoilage, viruses like norovirus can contaminate food and lead to illness.